Press working apparatus

Abstract

A press working apparatus according to the present disclosure punches a workpiece and comprises: a punch which moves in the pressing direction, and has a pressing surface facing the workpiece and a side surface connected to the pressing surface; a die which has a hollow section where the punch is inserted, and on which the workpiece is placed; a sensor which detects a load applied to the punch; and a control unit which controls the punch, die, and sensor. The control unit generates, on the basis of the load detected by the sensor, a load waveform indicating the relationship between the load and time from the time when the punching is started until the time when the punching is ended, and calculates a wear amount of the punch on the basis of a maximum value of the load in the load waveform and a change in time required to reach the maximum value of the load.

Description

Press Processing Equipment

[0001] The present disclosure relates to a press working device.

[0002] 2. Description of the Related Art In press working for punching a plate-shaped workpiece, a device for measuring the processing resistance when punching the workpiece is known.

[0003] The punching characteristic measuring device described in Patent Document 1 measures the punching force during punching by converting the change over time in deformation of the frame during punching into an electrical signal.

[0004] Japanese Unexamined Patent Publication No. 62-40938

[0005] The punching characteristic measuring device described in Patent Document 1 has room for improvement in terms of improving the accuracy of calculating the amount of wear of the tool.

[0006] The present disclosure provides a press working device that can improve the accuracy of calculating the amount of wear of a punch.

[0007] A press processing apparatus according to one aspect of the present disclosure is a press processing apparatus that performs punching on a workpiece, and includes: a punch that moves in a press direction and has a press surface facing the workpiece and a side surface connected to the press surface; a die that has a hollow portion into which the punch is inserted and on which the workpiece is placed; a sensor that detects the load acting on the punch; and a control unit that controls the punch, the die, and the sensor, wherein the control unit generates a load waveform that shows the relationship between the load and time from the start time to the end time of the punching process based on the load detected by the sensor, and calculates the amount of wear on the punch based on the maximum value of the load in the load waveform and the change in time until the maximum value of the load is reached.

[0008] According to the present disclosure, it is possible to provide a press working device that can improve the accuracy of calculating the amount of wear of a punch.

[0009] Schematic diagram showing a press working apparatus according to a first embodiment of the present disclosure. Schematic diagram showing a bottom dead center state of a punch in the press working apparatus of FIG. 1. Top view showing a sensor of the press working apparatus of FIG. 1. Flowchart explaining a process for determining whether or not grinding of a punch is necessary in a press working apparatus. Schematic diagram showing a process for punching a workpiece in a press working apparatus. Schematic diagram showing a process for punching a workpiece in a press working apparatus. Schematic diagram showing a process for punching a workpiece in a press working apparatus. Schematic diagram showing a process for punching a workpiece in a press working apparatus. Graph showing a load waveform generated based on loads detected by each of four sensors. Graph in which a load waveform when wear of the punch progresses is superimposed on the load waveform of FIG. 6. Graph showing an example of the relationship between the impulse of the punch and a first wear amount on the press surface of the punch. Graph showing an example of the relationship between the maximum load of the stable waveform portion in a second period and a second wear amount on the side surface of the punch 1.

[0010] (Background to the Invention) Press working, which performs punching on a plate-shaped workpiece, is generally a technique for obtaining a predetermined shape by pressing the workpiece loaded on a die with a stripper and forcing a part of the workpiece into the die with a punch, thereby punching it out. Press working by punching is generally used in a wide range of fields, such as home appliances, precision machinery, and automobile parts.

[0011] In press processing by punching, punching characteristic measuring devices are known that measure the punching force during punching by converting the change over time in frame deformation during punching into an electrical signal, such as the punching characteristic measuring device described in Patent Document 1.

[0012] The punching characteristic measuring device described in Patent Document 1 converts frame deformation during punching into an electrical signal to measure the punching force during punching. The punching force is the resistance force when a die punches a laminate. As the die wears, the punching force increases, so it has been studied to use the punching force to calculate the die wear state and determine whether the tool needs to be re-ground.

[0013] However, the punching characteristic measuring device described in Patent Document 1 detects deformation of the frame at a position away from the processing position of the die, which has the problem that it is not possible to calculate the wear state of the die with high accuracy.

[0014] The present inventor(s) have investigated a press working device that can accurately calculate the amount of wear of a punch, and have arrived at the following invention.

[0015] A press processing apparatus according to a first aspect of the present disclosure is a press processing apparatus that performs punching on a workpiece, and includes: a punch that moves in a press direction and has a press surface facing the workpiece and a side surface connected to the press surface; a die that has a hollow portion into which the punch is inserted and on which the workpiece is placed; a sensor that detects the load applied to the punch; and a control unit that controls the punch, the die, and the sensor, wherein the control unit generates a load waveform that shows the relationship between the load and time from the start to the end of punching based on the load detected by the sensor, and calculates the amount of wear of the punch based on the maximum value of the load in the load waveform and the change in time until the load reaches the maximum value.

[0016] With this configuration, it is possible to provide a press working device that can improve the accuracy of calculating the amount of wear of the punch.

[0017] In the press processing apparatus according to the second aspect of the present disclosure, the control unit may calculate a first wear amount of the press surface of the punch based on the waveform of the load waveform during a first period from the start of the punching process to a minimum time when the load reaches its maximum value and then its minimum value, and calculate a second wear amount of the side surface of the punch based on the waveform of the load waveform during a second period from the minimum time to the end of the punching process.

[0018] With this configuration, the amount of wear on the pressing surface and side surface of the punch can be calculated with high accuracy.

[0019] In the stamping apparatus according to the third aspect of the present disclosure, the control unit may calculate an impulse applied to the punch in the first period based on the load waveform, and calculate the first wear amount based on the calculated impulse.

[0020] With this configuration, the amount of wear on the pressing surface of the punch can be calculated with high accuracy.

[0021] In the press processing device according to the fourth aspect of the present disclosure, the load waveform has, during the second period, a vibration waveform section in which the load changes, and a stable waveform section following the vibration waveform section in which the change in the load is smaller than that in the vibration waveform section, and the control section may calculate the second wear amount based on the maximum load in the stable waveform section.

[0022] With this configuration, the amount of wear on the side surface of the punch can be calculated with high accuracy.

[0023] In the stamping apparatus according to the fifth aspect of the present disclosure, the control unit may determine to grind the press surface of the punch when the first wear amount is greater than a predetermined first threshold value.

[0024] With this configuration, it is possible to accurately determine whether or not polishing of the pressing surface of the punch is necessary.

[0025] In the stamping apparatus according to a sixth aspect of the present disclosure, the control unit may determine to grind the side surface of the punch when the second wear amount is greater than a predetermined second threshold value.

[0026] With this configuration, it is possible to accurately determine whether or not the side surface of the punch needs to be polished.

[0027] In the stamping device according to the seventh aspect of the present disclosure, the first threshold value may be greater than the second threshold value.

[0028] With this configuration, it is possible to accurately determine whether or not the punch needs to be polished.

[0029] In the stamping device according to the eighth aspect of the present disclosure, the sensor may include a plurality of sensors that detect the load.

[0030] With this configuration, the load acting on the punch can be detected locally, and it is possible to more accurately determine whether or not the punch needs to be polished.

[0031] The stamping device according to a ninth aspect of the present disclosure may further include a gap sensor that detects the position of the punch.

[0032] This configuration makes it possible to determine whether the relative position of the punch with respect to the die is appropriate and to start measuring the load on the punch at an appropriate timing, thereby making it possible to more accurately determine whether the punch needs to be polished.

[0033] Hereinafter, an embodiment will be described with reference to the drawings.

[0034] (First embodiment) [Overall configuration] Fig. 1 is a schematic diagram showing a stamping apparatus 100 according to a first embodiment of the present disclosure. Fig. 2 is a schematic diagram showing a bottom dead center state of the punch 1 in the stamping apparatus 100 of Fig. 1. Fig. 3 is a top view showing the sensor 6 of the stamping apparatus 100 of Fig. 1. Note that some components are omitted from Figs. 2 and 3. The stamping apparatus 100 according to this embodiment will be described with reference to Figs. 1 to 3.

[0035] The X-Y-Z coordinate system shown in each drawing is for facilitating understanding of the embodiment and does not limit the embodiment. In each drawing, the X direction is the width direction of the press working apparatus 100, the Y direction is the depth direction of the press working apparatus 100, and the Z direction is the height direction of the press working apparatus 100.

[0036] The press working device 100 is equipped with a punch 1, a die 2, a sensor 6, and a control unit 18, and is a device that performs punching on a plate-shaped workpiece 5.

[0037] The press working apparatus 100 is, for example, a servo screw press that can be controlled with high precision. In this embodiment, the press working apparatus 100 includes a press body 9 and a control unit 18. The press body 9 includes a punch 1, a die 2, and a sensor 6.

[0038] 1, the press body 9 of the press working device 100 has an upper die including a punch 1 attached to a slide 7, and a lower die including a die 2 attached to a bolster 8. Based on commands from a control unit 18, the press body 9 rotates a ball screw 12 connected to a servo motor 11 to drive the slide 7 up and down in the press direction (Z direction) along a shaft 10 at a predetermined speed. This operation of the press body 9 allows the workpiece 5 to be punched.

[0039] The punch 1 is a tool that moves in the press direction (Z direction) to punch the workpiece 5. As shown in FIG. 2, the punch 1 has a press surface 1a that faces the workpiece 5 and a side surface 1b that connects to the press surface 1a. The punch 1 is attached to a slide 7 together with a stripper plate 3 that presses the workpiece 5 against the die 2 during punching. As the slide 7 moves, the punch 1 is pressed against the workpiece 5 to perform the punching process. In this embodiment, as shown in FIG. 3, the punch 1 has a circular press surface 1a. This allows the workpiece 5 to be punched into a circular shape.

[0040] In this embodiment, the punch 1 is cylindrically shaped with a circular press surface 1a having a diameter of 4.5 mm and punches a circular hole in the workpiece 5. The punch 1 is made of, for example, a superhard material. The term "superhard material" refers to an artificial metal (alloy) formed by bonding nine types of carbides—W (tungsten), Cr (chromium), Mo (molybdenum), Ti (titanium), Zr (zirconium), Hf (hafnium), V (vanadium), Nb (niobium), and Ta (tantalum)—with an Fe-group metal (Fe, Co, or Ni). In other words, a superhard material refers to an alloy with extremely high hardness. For example, an alloy equivalent to VM-40 of the Cemented Carbide Tool Manufacturers Association (CIS) standard can be used as the superhard material.

[0041] As shown in Fig. 2, a workpiece 5 is placed on the die 2 during punching. The die 2 has a hollow portion 2a into which the punch 1 is inserted. The hollow portion 2a is a through-hole that passes through the die 2 in the Z direction. The die 2 is attached to a bolster 8 together with a die plate 4 that holds the die 2. Like the punch 1, the die 2 is made of, for example, a superhard material.

[0042] The workpiece 5 is a plate-shaped material to be processed by the press processing device 100. A plurality of workpieces 5 are transported in the X direction or the Y direction by a transport unit (not shown) in accordance with the pressing operation of the press device main body 9, and are sequentially punched.

[0043] In this embodiment, the workpiece 5 is made of SUS301-EH material, which is a type of steel classified as austenitic stainless steel. SUS301-EH material is a material used, for example, for mainsprings or springs in automobile parts. In this embodiment, the workpiece 5 has a thickness of 0.031 mm, a hardness of 529 HV, and a tensile strength of 1,679 N / mm ２ is.

[0044] The sensor 6 is a load sensor that detects the load applied to the punch 1. In this embodiment, the sensor 6 detects the load applied in the press direction (Z direction) of the punch 1. The sensor 6 detects the load applied in the press direction (Z direction) of the punch 1 when punching the workpiece 5. Specifically, the sensor 6 detects a reaction force P (see FIG. 2 ) in the press direction (Z direction) of the punch 1 when punching the workpiece 5.

[0045] As shown in Figure 3, in this embodiment, the sensor 6 includes four sensors 6a to 6d. In addition, in this embodiment, the sensors 6a and 6b are arranged symmetrically in the Y direction, and the sensors 6c and 6d are arranged symmetrically in the X direction. In this embodiment, the four sensors 6a to 6d are arranged on concentric circles. By arranging the four sensors 6a to 6d in this manner, it becomes easier to determine which parts of the punch 1 are worn.

[0046] The control unit 18 controls the punch 1, the die 2, and the sensor 6. In this embodiment, the control unit 18 has a press controller 14, a sensor controller 15, a calculation unit 16, and a determination unit 17. The control unit 18 is configured with digital circuits such as a microcomputer, a CPU, an MPU, a GPU, a DSP, an FPGA, an ASIC, etc.

[0047] The press controller 14 drives the servo motor 11 to rotate the ball screw 12, thereby driving the slide 7 up and down in the press direction (Z direction) at a predetermined speed.

[0048] The sensor controller 15 is electrically connected to the sensor 6 of the punch 1 and a gap sensor 13 (described later), and outputs the detection values ​​of the sensors 6 and 13 to the calculation unit 16 .

[0049] The calculation unit 16 generates a load waveform showing the relationship between the load applied to the punch 1 and time based on the load detected by the sensor 6, and calculates the amount of wear of the punch 1 based on the load waveform. Repeated punching operations gradually wear the punch 1. The calculation unit 16 calculates the amount of wear of the press surface 1 a and side surface 1 b of the punch 1. The generation of the load waveform and the calculation of the amount of wear will be described in detail below.

[0050] The determination unit 17 determines whether or not grinding of the punch 1 is necessary based on the amount of wear of the press surface 1 a and the side surface 1 b calculated by the calculation unit 16. As the amount of wear of the punch 1 increases, the accuracy of the punching dimensions of the workpiece 5 gradually deteriorates. For this reason, it is advisable to grind the punch 1 when the amount of wear exceeds a predetermined threshold. When the determination unit 17 determines that the punch 1 should be ground, it outputs a signal to the press controller 14 to interrupt the punching process. Upon receiving the notification, the press controller 14 stops the servo motor 11 and interrupts the punching process.

[0051] In this embodiment, the stamping apparatus 100 includes a gap sensor 13 that detects the position of the punch 1. More specifically, the gap sensor 13 can detect whether the punch 1 shown in FIG. 2 is in the lowest possible position, i.e., the bottom dead center state. The gap sensor 13 can also detect how much the punch 1 has risen from the bottom dead center state. The gap sensor 13 can be configured, for example, by a displacement sensor that measures a minute distance between the punch 1 and an object to be measured in a non-contact manner.

[0052] The gap sensor 13 is attached to a desired position on the lower die of the press working apparatus 100, which includes, for example, the die 2, the die plate 4, and the bolster 8. The gap sensor 13 detects contact with the upper die, which includes the punch 1, the stripper plate 3, and the slide 7, thereby detecting that the punch 1 is at its bottom dead center. The gap sensor 13 can also determine the start timing for detecting the load on the punch 1. Specifically, the start timing can be determined based on the gap of the gap sensor 13 and the position of the punch 1 from its bottom dead center position so that detection of the load on the punch 1 can be started at the same timing for each punching shot. In this way, the gap sensor 13 can be used as a trigger for detecting the load on the punch 1. Furthermore, by arranging the gap sensors 13 at each of the four corners of the lower die, it can be detected whether the upper die and the lower die are arranged parallel to each other. The gap sensor 13 is not an essential component, and the press working apparatus 100 does not necessarily have to include the gap sensor 13.

[0053] [Determining Whether or Not Grinding of Punch is Necessary] Fig. 4 is a flowchart illustrating processing for determining whether or not grinding of the punch 1 is necessary in the press working apparatus 100. The determination of whether or not grinding of the punch 1 is necessary will be described with reference to Fig. 4 .

[0054] In the press working device 100, when punching is started, the sensor 6 detects the load applied to the punch 1 in the pressing direction (Z direction) (step S1). In this embodiment, the load is detected by each of the four sensors 6a to 6d.

[0055] The load detected by the sensor 6 is output to the calculation unit 16 via the sensor controller 15 of the control unit 18. The calculation unit 16 generates a load waveform that indicates the relationship between the load applied to the punch 1 and time (step S2).

[0056] 5A to 5D are schematic diagrams showing the process of punching a workpiece 5 using the press working device 100. FIG. 6 is a graph showing an overlapping of load waveforms generated based on the loads detected by each of the four sensors 6a to 6d. The load waveforms will be explained with reference to FIGS. 5A to 6. The dashed line in FIG. 7 shows the load waveform when the punch 1 is almost not worn.

[0057] When punching begins, punch 1 descends in the Z direction from the top dead center position until it contacts the workpiece 5 ( FIG. 5A ). The top dead center position refers to the highest position punch 1 can assume. In the graph of FIG. 6 , time C1 is the point at which punch 1 contacts the workpiece 5 and the load on punch 1 becomes greater than zero. Once punch 1 contacts the workpiece 5, punch 1 begins punching the workpiece 5, as shown in FIG. 5B . Therefore, a load begins to be applied to punch 1 from time C1, and the load on punch 1 increases rapidly, reaching a maximum value P0 at time m1. Thereafter, as shown in FIG. 5C , once punch 1 cuts the workpiece 5, the load on punch 1 drops to near zero, becoming a minimum value. The point at which the load on punch 1 reaches a value close to zero is time C2 (minimum time) in FIG. 6 . The minimum time C2 refers to the point at which the load on punch 1 drops to near zero within a predetermined period after the load on punch 1 reaches its maximum value P0. The load on the punch 1 drops to near 0 because the resistance to the punch 1 decreases as the punch 1 punches through the workpiece 5. Note that even when the workpiece 5 is cut, the load on the punch 1 detected by the sensor 6 may not reach 0 due to vibration of the punch 1 or other external factors.

[0058] After the load on the punch 1 reaches a minimum value, interference between the punch 1 and the die 2 or disturbances such as the workpiece 5 cause the punch 1 and the die 2 to come into contact, applying a load to the punch 1. For example, the punch 1 or the die 2 may tilt, causing the punch 1 and the die 2 to come into contact and applying a load to the punch 1. Alternatively, the workpiece 5 after cutting may be pulled between the punch 1 and the die 2 (see FIG. 5D), causing a load to be applied to the punch 1. After that, the load is applied to the punch 1 for a while, and then the load on the punch 1 becomes zero. The point at which the load on the punch 1 becomes zero is time C3 in FIG. 6.

[0059] When the amount of wear on the punch 1 is small, that is, when the punch 1 has just been polished, the load waveforms from the sensors 6a to 6d are superimposed and have approximately the same shape, as shown in Figure 6. Note that due to subtle changes in the clearance between the punch 1 and the die 2, the load waveforms from the sensors 6a to 6d often differ slightly, as shown in Figure 6.

[0060] 4, after the load waveform is generated by the calculation unit 16 in step S2, the calculation unit 16 calculates the wear amount of the punch 1 (step S3). The wear amount of the punch 1 is calculated based on the respective load waveforms shown in FIG.

[0061] During the period from the start of punching (time C1) to minimum time C2 when the load reaches its maximum value P0 and then its minimum value, i.e., the period from when the punch 1 comes into contact with the workpiece 5 until the workpiece 5 is cut, the load is mainly applied to the press surface 1a of the punch 1. The period from the start of punching to minimum time C2 when the load reaches its maximum value P0 and then its minimum value is the first period T0, and the amount of wear on the press surface 1a of the punch 1 is calculated based on the waveform of the load waveform during the first period T0.

[0062] During the period from minimum time C2 to the end of punching (time C3), i.e., the period from when the workpiece 5 is cut until the load on the punch becomes zero, the load is mainly applied to the side surface 1b of the punch 1. The period from minimum time C2 to the end of punching (time C3) is the second period Ts0. During the second period Ts0, the load is applied to the side surface 1b of the punch 1 due to interference between the punch 1 and the die 2 or the cut workpiece 5 being pulled between the punch 1 and the die 2. As shown in FIG. 6 , during the second period Ts0, the load waveform has a vibration waveform portion in which the load changes and a stable waveform portion following the vibration waveform portion, in which the load changes less than in the vibration waveform portion. The wear amount of the side surface 1b of the punch 1 is calculated based on the waveform of the load waveform during the second period. Note that the change in load is smaller in the stable waveform portion than in the vibration waveform portion means that the change in load per given time is smaller in the stable waveform portion than in the vibration waveform portion.

[0063] The sensors 6a to 6d are fixed to the punch 1 shown in FIG. 2, and a gap is formed between the sensors 6a to 6d and the plate 19. When punching of the workpiece 5 is complete, the loads acting on the sensors 6a to 6d become close to zero. Thereafter, due to the gap between the sensors 6a to 6d and the plate 19, the reaction force from punching the workpiece 5 causes the sensors 6a to 6d to collide with and separate from the plate 19. The load detected at this time appears in the vibration waveform section. After the reaction force from punching the workpiece 5 subsides, the punch 1 reaches the bottom dead center state with the workpiece 5 and the side surface 1b of the punch 1 in contact. The load detected at this time appears in the stable waveform section.

[0064] The load applied to the punch 1 increases as the wear of the punch 1 progresses due to repeated punching operations. Fig. 7 is a graph in which the load waveform when the wear of the punch 1 progresses is superimposed on the load waveform when the wear of the punch 1 progresses, as shown in Fig. 6.

[0065] 7, as wear of the punch 1 progresses, the maximum load applied to the punch 1 increases from maximum value P0 to maximum value P1. Furthermore, as wear of the punch 1 progresses, the minimum time shifts from time C2 to time C4. Therefore, as wear of the punch 1 progresses, the maximum load applied to the punch 1 increases from maximum value P0 to maximum value P1, and the first period T1 of the load waveform when wear of the punch 1 progresses becomes longer than the first period T0 of the load waveform when the punch 1 is not worn.

[0066] 7, as the wear of the punch 1 progresses, the minimum time shifts from time C2 to time C4, and the second period in the load waveform changes from period Ts0 to period Ts1. As the wear of the side surface 1b of the punch 1 progresses, the length of the second period shortens. That is, period Ts1 becomes shorter than period Ts0. Furthermore, the maximum load of the punch 1 in the stable waveform portion increases from maximum value Ps0 to maximum value Ps1.

[0067] Here, we will explain how to calculate the wear amount of the punch 1 based on the load waveform. The wear amount of the punch 1 includes a first wear amount of the press surface 1 a of the punch 1 and a second wear amount of the side surface 1 b of the punch 1. In this embodiment, the first wear amount of the press surface 1 a and the second wear amount of the side surface 1 b are calculated separately.

[0068] The first wear amount of the press surface 1a of the punch 1 can be calculated based on the impulse of the punch 1 during the first periods T0 and T1. The impulse of the punch 1 is the product of the load applied to the punch 1 and time, and is expressed by the area of ​​the load waveform during the first periods T0 and T1. In other words, the impulse can be calculated based on the load waveform.

[0069] When a workpiece 5 made of SUS301-EH material and having a thickness of 0.031 mm is punched at an instantaneous punching speed of 3 mm / s without press oil, the relationship shown in formula (1) holds between the impulse D of the punch 1 and the first wear amount a of the press surface 1 a of the punch 1.

[0070] [Equation 1] D = 4 × 10 －５ ×a ３ -0.0005 x a ２+0.003×a+3.6 (1) Fig. 8 is a graph showing an example of the relationship between the impulse D of the punch 1 and the first wear amount a of the press surface 1a of the punch 1. From equation (1) and Fig. 8, for example, when the impulse of the punch 1 is 4 Nms, it can be calculated that the first wear amount a of the press surface 1a of the punch 1 is 23 µm.

[0071] The second wear amount of the side surface 1b of the punch 1 can be calculated based on the maximum loads Ps0 and Ps1 of the stable waveform portion in the second periods Ts0 and Ts1.

[0072] When a workpiece 5 made of SUS301-EH material and having a thickness of 0.031 mm is punched at an instantaneous punching speed of 3 mm / s without press oil, the relationship expressed by equation (2) holds between the maximum load Ps of the punch 1 during the second periods Ts0 and Ts1 and the second wear amount b of the side surface 1b of the punch 1.

[0073] [Math 2] Ps=33.333×b ３ -10 x b ２ +6.6667×b+75 (2) Fig. 9 is a graph showing an example of the relationship between the maximum load Ps of the stable waveform portion in the second periods Ts0 and Ts1 and the second wear amount b of the side surface 1b of the punch 1. From equation (2) and Fig. 9, for example, when the maximum load Ps is 130 N, the second wear amount b of the side surface 1b of the punch 1 can be calculated to be 1.25 µm.

[0074] As described above, the calculation unit 16 calculates the first wear amount a of the press surface 1a based on the impulse of the punch 1 during the first period T0 in the load waveform, and calculates the second wear amount b of the side surface 1b based on the maximum load Ps in the stable waveform portion during the second period Ts0 in the load waveform. In this embodiment, the stamping device 100 has four sensors 6a to 6d, and generates the four load waveforms shown in Figure 6. Therefore, the first wear amount a and the second wear amount b are calculated for each of the four load waveforms.

[0075] For example, in multi-layer punching, in which multiple workpieces 5 are stacked and punched simultaneously, the workpieces 5 tend to be cut by fracture rather than shear, which increases the load on the press surface 1a of the punch 1. For this reason, as punching is repeated, the impulse in the first period T0 of the load waveform increases significantly. Therefore, in multi-layer punching, the first wear amount a can be calculated more accurately based on the change in the impulse in the first period T0 of the load waveform.

[0076] Returning to FIG. 4, once the calculation unit 16 has calculated the wear amount of the punch 1 (step S3), the determination unit 17 determines whether or not the punch 1 needs to be polished (step S4).

[0077] The determination unit 17 determines whether or not the punch 1 needs to be polished based on whether or not the first wear amount a of the press surface 1a and the second wear amount b of the side surface 1b each exceed a threshold value.

[0078] If the first wear amount a is greater than a predetermined first threshold value or if the second wear amount b is greater than a predetermined second threshold value, the determination unit 17 determines that the punch 1 is to be polished (Yes in step S4). In this embodiment, if at least one of the first wear amounts a for each of the four load waveforms is greater than the first threshold value or if at least one of the second wear amounts b for each of the four load waveforms is greater than the second threshold value, the determination unit 17 determines that the punch 1 is to be polished.

[0079] When the amount of wear was measured when a 5 μm burr was generated on the punched product, the first amount of wear on the press surface 1 a was 23 μm, and the second amount of wear on the side surface 1 b was 1.25 μm. Therefore, assuming that the allowable range of burr size is 5 μm, the maximum allowable value of the first amount of wear a can be defined as 23 μm, and the maximum allowable value of the second amount of wear b can be defined as 1.25 μm. Therefore, in this case, the first threshold value is 23 μm, and the second threshold value is 1.25 μm. The maximum values ​​of the first amount of wear a and the second amount of wear b, i.e., the first threshold value and the second threshold value, are determined in advance based on the allowable size of the burr, the material of the workpiece 5 or the punch 1 and die 2, and processing conditions such as the punching speed and the presence or absence of press oil.

[0080] In the case of punching, wear generally progresses faster on the press surface 1a of the punch 1 than on the side surface 1b of the punch 1. This is because a greater load is applied to the press surface 1a of the punch 1 than to the side surface 1b during punching. As shown in the load waveform in Figure 6, the maximum load P0 in the first period T0 is greater than the maximum load Ps0 in the stable waveform portion of the second period Ts0, which also indicates that the load applied to the press surface 1a is greater than the load applied to the side surface 1b. For this reason, the first threshold value is set to a value greater than the second threshold value.

[0081] If the determination unit 17 determines that the punch 1 should be ground (Yes in step S4), the press controller 14 stops the operation of the press processing device 100, interrupts the punching process, and ends the process of determining whether or not it is necessary to ground the punch 1. If the determination unit 17 determines that the punch 1 should not be ground (No in step S4), the punching process continues and the process returns to step S1.

[0082] In step S4, if any one or more of the first wear amounts a calculated from the load waveforms obtained by the four sensors 6a to 6d exceeds a first threshold, the punching process is interrupted. Similarly, if any one or more of the second wear amounts b calculated from the load waveforms obtained by the four sensors 6a to 6d exceeds a second threshold, the punching process is interrupted.

[0083] [Effect] According to the above-described embodiment, a press working apparatus capable of accurately calculating the amount of wear of the punch 1 can be provided. In the press working apparatus 100, the sensor 6 detects the load applied to the punch 1. A load waveform is generated based on the detected load. The load waveform has a first period T0 during which the load is applied mainly to the press surface 1a of the punch 1 and a second period Ts0 during which the load is applied mainly to the side surface 1b of the punch 1. The amount of wear of the punch 1 is calculated based on the maximum value of the load in the load waveform and the change in time until the load reaches the maximum value. More specifically, a first amount of wear a of the press surface 1a of the punch 1 is calculated based on the waveform in the first period T0, and a second amount of wear b of the side surface 1b of the punch 1 is calculated based on the waveform in the second period Ts0. In this way, the amounts of wear of the press surface 1a and the side surface 1b can be calculated from the load waveform, thereby enabling accurate calculation of the amount of wear of the punch 1.

[0084] Furthermore, since the necessity of grinding the punch is determined based on the first wear amount a and the second wear amount b of the punch 1, the accuracy of determining the necessity of grinding can be improved.

[0085] In the above embodiment, the workpiece 5 is made of SUS301-EH material, but the workpiece 5 is not limited to this material. The workpiece 5 can be made of various metal materials.

[0086] In the above embodiment, an example in which four sensors 6a to 6d are arranged on the punch 1 has been described, but the number of sensors is not limited to this. It is sufficient that the number of sensors is one or more.

[0087] In the above-described embodiment, the punch 1 has a circular pressing surface 1 a, but the present invention is not limited to this. The shape of the pressing surface 1 a is not limited to a circle, and may be any shape such as a polygon or an ellipse.

[0088] Furthermore, in the above-described embodiment, an example has been described in which it is determined that the punch 1 should be ground when the first wear amount a of the press surface 1 a is greater than the first threshold value, but the present invention is not limited to this. As shown in the graph of Fig. 8, based on the relationship between the impulse D of the punch 1 and the first wear amount a of the press surface 1 a, it may be determined that the punch 1 should be ground when the impulse D of the punch 1 is greater than a predetermined threshold value.

[0089] In the above-described embodiment, the punch 1 is determined to be ground when the second wear amount b of the side surface 1 b is greater than the second threshold value, but the present invention is not limited to this. As shown in the graph of Fig. 9, the punch 1 may be determined to be ground when the maximum load in the stable waveform portion of the second period is greater than a predetermined threshold value.

[0090] The press working device of the present disclosure is useful as a device for punching any workpiece used in home appliances, medical equipment, etc.

[0091] DESCRIPTION OF SYMBOLS 1 punch 1a press surface 1b side surface 2 die 2a hollow portion 3 stripper plate 4 die plate 5 workpiece 6, 6a to 6d sensor 7 slide 8 bolster 9 press device body 10 shaft 11 servo motor 13 gap sensor 14 press controller 15 sensor controller 16 calculation unit 17 determination unit 18 control unit 100 press processing device

Claims

1. A press working apparatus for performing punching on a workpiece, a punch that moves in the press direction and has a press surface facing the workpiece and a side surface connected to the press surface, a die having a hollow portion into which the punch is inserted and on which the workpiece is placed, a sensor for detecting the load applied to the punch, and a control unit for controlling the punch, the die, and the sensor, The control unit, based on the load detected by the sensor, generates a load waveform showing the relationship between the load and time from the start time to the end time of the punching process, calculates the wear amount of the punch based on the maximum value of the load in the load waveform and the change in time until the maximum value of the load is reached, A press working apparatus.

2. The control unit, based on the waveform of the first period in the load waveform from the start time of the punching process to the minimum time when the minimum value of the load is reached after the maximum value of the load is reached, calculates the first wear amount of the press surface of the punch, based on the waveform of the second period in the load waveform from the minimum time to the end time of the punching process, calculates the second wear amount of the side surface of the punch, The press working apparatus according to claim 1.

3. The control unit calculates the force integral applied to the punch in the first period based on the load waveform, and calculates the first wear amount based on the calculated force integral, The press working apparatus according to claim 2.

4. The load waveform, in the second period, has a vibration waveform portion in which the load changes, and a stable waveform portion that follows the vibration waveform portion and has a smaller load change than the vibration waveform portion, The control unit calculates the second wear amount based on the maximum load of the stable waveform part. The press working apparatus according to claim 2.

5. The control unit When the first wear amount is greater than a predetermined first threshold value, it determines that the press surface of the punch is polished. The press working apparatus according to claim 2.

6. The control unit When the second wear amount is greater than a predetermined second threshold value, it determines that the side surface of the punch is polished. The press working apparatus according to claim 5.

7. The first threshold value is greater than the second threshold value. The press working apparatus according to claim 6.

8. The sensor includes a plurality of sensors that detect the load. The press working apparatus according to claim 1.

9. Furthermore, a gap sensor that detects the position of the punch is provided. The press working apparatus according to any one of claims 1 to 8.